I would like to use soil humidity sensor as a switch to power on small dc 5v pump without arduino.
The problem Im facing is that when I dont have 5v pump connected the output pin reads 5V like it should, but at the moment I connect pump voltage drops at 0.2V on digital and 0V on analog pin.
What am I doing wrong, what I need to do. Should I add capacitor between output pin and pump or ?
Also I have same problem with 20 usd action camera, the first problem I had is when it gets power it does not power on, to solve that I got ne555 delay timer to triger power on switch when there is current.
When I power the camera with 2nd external 5V power it works ok, but when I use same power source for both camera and ne555 delay timer it does not switch, the lights are on but relay does not switch.
I have a feeling that these two problems are connected and I really have no idea how to fix them, I could search over internet for days and mybe never find out but I would really appreciate if you could save me the trouble with solution.
You can not run a pump off a sensor. You'll need at the very least some form of electronic switch.
Next problem: there will be a long delay between the pump starting to pump, and water reaching the sensor. By the time the sensor realises it's getting moist, chances are that your reservoir has been pumped empty and most of the contents have spilled on the floor.
A sensor is a sensor, a switch is a switch. Two different things. You can not switch a pump directly from a sensor. You need something that reads the sensor and operates the switch. A 555 chip would actually be very capable of doing just that (it's not just a timer), you still have the problem of the delay between having enough water in the pot and the sensor sensing this.
Other than that, it sounds like you're not having a powerful enough power supply.
I have 12V 5A power supply, that I transform into 5V 2A max. 3A, and pump only needs 0.1-0.2A
Im not using this with pots but cause I bought this sensor instead of water level and Im learining how to do things in electronics
before I had schematics for making pir sensor into 12v switch by using mosfet, do you know how to use these to solve above problem
Pretty much like that, except that the 555 can't supply enough current for your relay, you need a driver transistor (or MOSFET) in between. In case of MOSFET make sure you have a logic level gate, or it won't switch on properly. For these currents I'd use a simple transistor instead.
You can wire the 555 as switch with hysteresis (it switches at 1/3 and 2/3 Vdd level so you can have it switch on when the sensor value drops below 1/3 Vdd and off again when the sensor is at 2/3 Vdd); use Google for specific circuit diagrams. And find a way to have your moisture sensor react fast enough to stop the pump in time.
Both are MOSFETs and neither are logic level one. Check the data sheets for details.
It seems the IRF9450N might open up enough to run your pump but you'll just have to try. Or get a logic level MOSFET such as the IRL540N that opens up fully at 5V gate.
The resistor doesn't drop the voltage. It limits current, which is important to protect the 555 (MOSFETs tend to have quite high gate capacities). Anything 100-10,000 Ohm should do the job. The smaller the faster the switching (but you're talking microseconds here, if that much).
Remember your MOSFET may not open up enough for your pump as you don't have a logic level version. So if it doesn't work, try connecting the gate directly to the 5V, if your pump still doesn't run get another MOSFET.
